I. Field of the Invention
This invention relates generally to sewing machine apparatus, and more particularly to a sewing machine especially designed to append binding or bias tape to the cut edge of a carpet to prevent fraying of that edge.
II. Description of the Related Art
When a piece of floor carpeting is cut from a larger roll, it is usually necessary to treat the cut edge to prevent the pile fibers of the carpet from unraveling or otherwise becoming frayed. One approach at treating the carpet edge is to affix binding tape about the cut edge, conventionally by longitudinally folding the binding tape over the cut edge and then sewing the binding tape to the carpet edge.
The closest prior art of which applicant is aware comprises a machine sold by the Newark Caplan Company of Newark, N.J. It is especially designed to sew a fabric binding tape onto the cut edge of the carpet. It comprises a motor-driven sewing machine, which is arranged to play out from a reel, a flat strip of binding fabric. It is fed through a former which causes the strip to be folded along a longitudinal midline of the tape as it is positioned over the edge of the carpeting. The sewing machine is conventional in the sense that it incorporates a thread-carrying bobbin beneath a baseplate, and mounted atop the baseplate is a sewing machine arm which supports a needle assembly for reciprocating vertical motion. The bobbin is generally stationary, but surrounding it is a rotatable hook which functions to pull a loop of thread from the sewing machine's reciprocating needle about the bobbin so as to capture the thread exiting the bobbin to create a lock-stitch. Because the carpeting is too large and heavy to be fed past a stationary sewing machine, the carpet binding machine sold by the Newark Caplan Company is wheel-mounted and designed to move along the floor of the room relative to the stationary carpet edge. The movement is achieved by providing a motor-driven, carpet-engaging roller disposed on the machine arm above the baseplate and adapted to engage the pile side of the carpeting. Exposed through an opening in the baseplate and cooperating with the carpet backing are conventional sewing machine feed dogs, which engage the carpet's backing material and move in synchronism with the upper drive rollers to step the machine along the carpet's edge as the sewing machine needle reciprocates to develop the lock stitches.
The Newark Caplan Company carpet binding machine suffers from a number of inherent design problems, including its propensity to: (1) damage the carpet, (2) "walk" off of the carpet edge; and (3) its difficulty to steer during use. Furthermore, needle breakage tends to be excessive.
Carpet damage is due to two separate problems. In the prior art Newark Caplan binding machine, the underside of the baseplate is totally open, such that many of the parts of the sewing machine that require lubrication are exposed. The oily surfaces, should they come into contact with the carpet being installed, can produce unsightly soiling. Moreover, the serrated feed dogs which engage the undersurface of the carpeting during use have been found to "chew up" certain backing materials, such as, sponge rubber foam.
The difficulty in steering and manipulating and the propensity of the machine to "walk" off the carpet edge is due to the configuration and placement of the serrated feed rollers which engage the pile surface of the carpeting. In the Newark Caplan machine, these feed rollers are offset a substantial distance in the downstream direction relative to the needle and only a fraction of the rollers actually engage the carpeting, with the remaining portion riding over the carpet edge. When it is considered that steering of the carpet binding machine during use involves having to pivot the machine about the reciprocating needle, the fact that the carpet-engaging drive rollers are displaced a substantial lateral distance downstream of the needle inhibits the ability of the operator to easily rotate the machine about the needle as a center. Compounding the steering problem is the fact that this prior art machine uses a pistol grip style handle affixed midway between the ends of the machine. This makes it more difficult to pivot at a carpet corner.
Because the Newark Caplan machine utilizes a conventional bifurcated presser foot to force the carpeting against the underlying feed dogs and because the needle reciprocates between the two prongs of the presser foot, it is subject to substantial sideways deflection should it strike a hard object, such as a bead of latex in the carpet backing. If the needle becomes deflected during its stroke, it may miss the aperture between the feed dogs through which it is intended to pass during its stroke, resulting in breakage.
It is accordingly a principal object of the present invention to obviate all of the foregoing drawbacks of the prior art carpet binding machine.
Another object of the invention is to provide a carpet binding machine for sewing binding tape along the edge of a carpet which does not cause damage to the carpet itself.
Still another object of the invention is to provide an improved carpet binding machine for sewing binding tape along the cut edge of a carpet which protects the carpet from soiling and which shields the working parts of the sewing machine from the build up of lint and other debris.
Yet another object of the present invention is to provide a carpet binding machine for sewing binding tape to the cut edge of a carpet which provides means for preventing needle breakage.
A still further object of the invention is to provide a carpet binding machine for sewing binding tape to the cut edge of a carpet where the machine may be more readily steered and less subject to walking off of the carpet edge.
A still further object of the invention is to provide a carpet binding machine for sewing binding tape to the cut edge of a carpet and which incorporates a needle guide for preventing sideways deflection of the needle during use.